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2ff639a0e6
The old implementation of Row::Element::pos2x and x2pos did not work correctly with Arabic text, because characters can have shapes that depend on context. This new implementation leverages QTextLayout in a simplified way, since only one word is added to the layout. This allows to make Row::Element::x2pos more readable. Fixes: #9115.
137 lines
4.2 KiB
C++
137 lines
4.2 KiB
C++
// -*- C++ -*-
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/**
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* \file FontMetrics.h
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* This file is part of LyX, the document processor.
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* Licence details can be found in the file COPYING.
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*
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* \author unknown
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* \author John Levon
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* \author Abdelrazak Younes
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*
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* Full author contact details are available in file CREDITS.
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*/
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#ifndef FONT_METRICS_H
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#define FONT_METRICS_H
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#include "support/strfwd.h"
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/**
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* A class holding helper functions for determining
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* the screen dimensions of fonts.
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*
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* The geometry is the standard typographical geometry,
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* as follows :
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*
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* --------------+------------------<maxAscent
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* | |
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* <-------> (right bearing)
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* <-> (left bearing)
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* char ascent>___ |
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* ^ oooo | oooo
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* origin>____ | oo oo | oo oo
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* \| oo oo | oo oo
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* --------------+---ooooo--|--oooo-<baseline
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* | oo |
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* char | oo oo |
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* descent>______| oooo |
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* <- width ->
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* --------------+----------+-------<maxDescent
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*
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* Caution: All char_type and docstring arguments of any method of this class
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* are no UCS4 chars or strings if the font is a symbol font. They simply
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* denote the code points of the font instead. You have to keep this in mind
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* when you implement the methods in a frontend. You must not pass these
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* parameters to a unicode conversion function in particular.
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*/
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namespace lyx {
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class Dimension;
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namespace frontend {
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class FontMetrics
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{
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public:
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virtual ~FontMetrics() {}
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/// return the maximum ascent of the font
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virtual int maxAscent() const = 0;
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/// return the maximum descent of the font
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virtual int maxDescent() const = 0;
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/// return default dimension of the font.
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/// \warning \c width is set to zero.
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virtual Dimension const defaultDimension() const = 0;
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/// return the width of the char in the font
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virtual int width(char_type c) const = 0;
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/// return the ascent of the char in the font
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virtual int ascent(char_type c) const = 0;
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/// return the descent of the char in the font
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virtual int descent(char_type c) const = 0;
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/// return the left bearing of the char in the font
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virtual int lbearing(char_type c) const = 0;
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/// return the right bearing of the char in the font
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virtual int rbearing(char_type c) const = 0;
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/// return the width of the string in the font
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virtual int width(docstring const & s) const = 0;
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/// FIXME ??
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virtual int signedWidth(docstring const & s) const = 0;
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/**
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* return the x offset of a position in the string. The
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* direction of the string is forced, and the returned value
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* is from the left edge of the word, not from the start of the string.
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*/
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virtual int pos2x(docstring const & s, int pos, bool rtl) const = 0;
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/**
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* return the position in the string for a given x offset. The
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* direction of the string is forced, and the returned value
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* is from the left edge of the word, not from the start of the string.
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* the offset x is updated to match the closest position in the string.
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*/
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virtual int x2pos(docstring const & s, int & x, bool rtl) const = 0;
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/// return char dimension for the font.
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virtual Dimension const dimension(char_type c) const = 0;
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/**
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* fill in width,ascent,descent with the values for the
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* given string in the font.
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*/
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virtual void rectText(docstring const & str,
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int & width,
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int & ascent,
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int & descent) const = 0;
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/**
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* fill in width,ascent,descent with the values for the
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* given string in the font for a button.
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*/
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virtual void buttonText(docstring const & str,
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int & width,
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int & ascent,
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int & descent) const = 0;
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/// return the maximum descent of the font
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inline int maxHeight() const { return maxAscent() + maxDescent(); }
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/// return the descent of the char in the font
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inline int height(char_type c) const { return ascent(c) + descent(c); }
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/// return the inner width of the char in the font
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inline int center(char_type c) const {
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return (rbearing(c) - lbearing(c)) / 2;
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}
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};
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} // namespace frontend
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class Font;
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class FontInfo;
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/// Implementation is in Application.cpp
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frontend::FontMetrics const & theFontMetrics(Font const & f);
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frontend::FontMetrics const & theFontMetrics(FontInfo const & fi);
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} // namespace lyx
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#endif // FONT_METRICS_H
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